Extended drain non-planar mosfets for electrostatic discharge (esd) protection

ABSTRACT

Snapback ESD protection device employing one or more non-planar metal-oxide-semiconductor transistors (MOSFETs) are described. The ESD protection devices may further include lightly-doped extended drain regions, the resistances of which may be capacitively controlled through control gates independent of a gate electrode held at a ground potential. Control gates may be floated or biased to modulate ESD protection device performance. In embodiments, a plurality of core circuits are protected with a plurality of non-planar MOSFET-based ESD protection devices with control gate potentials varying across the plurality.

This is a Continuation of application Ser. No. 14/795,854 filed Jul. 9,2015 which is a Continuation of application Ser. No.: 13/631,586 filedSep. 28, 2012 now U.S. Pat. No. 9,087,719 issued Jul. 21, 2015 which arehereby incorporated by reference.

TECHNICAL FIELD

Embodiments of the invention generally relate to electrostatic discharge(ESD) protection of integrated circuits (ICs), and more particularlyrelate to ESD protection devices employing non-planarmetal-oxide-semiconductor field effect transistors (MOSFETs).

BACKGROUND

ESD is a threat to IC reliability. Introduction of new materials in ICfabrication and the scaling of critical transistor interconnectdimensions and dielectrics have increased a circuit's susceptibility toESD events and degraded the capability to safely dissipate ESD charge.This technological trend poses even greater challenges for design ofeffective protection structures and circuit topologies. The need toreduce parasitic capacitance on high speed input/output lines of an ICchip (i.e., I/Os), as well as the need to reduce chip area consumed byESD protection circuits pose further challenges. Leakage currentsassociated with conventional ESD protection devices during normaloperation (i.e., when there is no ESD event) is another significantproblem for sub 32 nm technology nodes.

ESD protection devices in the art may be divided into two generalcategories: snapback devices and non-snapback devices. The most typicalnon-snapback devices are p-n junction diodes usually arranged in a dualdiode configuration where two diodes (P+/n and N+/p) are connected backto back and the pair further connected to an exposed I/O pin or pad.During an ESD event the diodes sink current so as to protect the I/Odevice and internal circuitry of the IC chip from damage, such as gateoxide breakdown, source-drain shorts, interlayer dielectric (ILD)breakdown, etc. The most typical snapback devices are transistor based,primarily MOSFETs. While snapback devices usually have relativelysmaller size and lower parasitic capacitance than non-snapbackimplementations, “off-state” source-drain leakage current is a biggerproblem for MOSFET-based designs, particularly at the 22 nm CMOStechnology node. An ESD protection snapback device which can conducthigher current (during ESD event) and provide lower leakage current(during normal operation) is therefore needed for 22 nm CMOS technologynode and beyond.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are illustrated by way of example,and not by way of limitation, and can be more fully understood withreference to the following detailed description when considered inconnection with the figures in which:

FIG. 1A is a sectioned isometric view of an extended drain non-planarMOSFET for electrostatic discharge (ESD) protection, in accordance withan embodiment of the present invention;

FIG. 1B is a sectioned isometric view of an extended drain non-planarMOSFET with a control gate for ESD protection, in accordance with anembodiment of the present invention;

FIG. 2A is a schematic of an extended drain non-planar MOSFET configuredfor ESD protection of CMOS circuitry coupled to an I/O pad, inaccordance with an embodiment;

FIG. 2B is a schematic of a plurality of extended drain non-planarMOSFETs configured for ESD protection of a plurality of CMOS circuitry,in accordance with embodiments;

FIG. 2C is a flow diagram illustrating operation of a plurality ofextended drain non-planar MOSFETs configured for ESD protection of aplurality of CMOS circuitry, in accordance with embodiments;

FIG. 3 is an I-V plot illustrating snap back characteristics for planarand non-planar MOSFET-based ESD protection devices during ESD events andnormal operation, in accordance with embodiments;

FIG. 4 is an isometric view of a mobile computing platform employing anIC with extended drain non-planar MOSFET ESD protection, in accordancewith an embodiment of the present invention; and

FIG. 5 is a functional block diagram of the mobile device illustrated inFIG. 4, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

In the following description, numerous details are set forth, however,it will be apparent to one skilled in the art, that the presentinvention may be practiced without these specific details. In someinstances, well-known methods and devices are shown in block diagramform, rather than in detail, to avoid obscuring the present invention.Reference throughout this specification to “an embodiment” or “in oneembodiment” means that a particular feature, structure, function, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the invention. Thus, the appearances ofthe phrase “in an embodiment” in various places throughout thisspecification are not necessarily referring to the same embodiment ofthe invention. Furthermore, the particular features, structures,functions, or characteristics may be combined in any suitable manner inone or more embodiments. For example, a first embodiment may be combinedwith a second embodiment anywhere the two embodiments are not specifiedto be mutually exclusive.

The terms “coupled” and “connected,” along with their derivatives, maybe used herein to describe structural relationships between components.It should be understood that these terms are not intended as synonymsfor each other. Rather, in particular embodiments, “connected” may beused to indicate that two or more elements are in direct physical orelectrical contact with each other. “Coupled” my be used to indicatedthat two or more elements are in either direct or indirect (with otherintervening elements between them) physical or electrical contact witheach other, and/or that the two or more elements co-operate or interactwith each other (e.g., as in a cause an effect relationship).

The terms “over,” “under,” “between,” and “on” as used herein refer to arelative position of one material layer or component with respect toother layers or components. For example, one layer disposed over orunder another layer may be directly in contact with the other layer ormay have one or more intervening layers. Moreover, one layer disposedbetween two layers may be directly in contact with the two layers or mayhave one or more intervening layers. In contrast, a first layer “on” asecond layer is in direct contact with that second layer. Similarly,unless explicitly stated otherwise, one feature disposed between twofeatures may be in direct contact with the adjacent features or may haveone or more intervening features.

In embodiments, a snapback ESD protection device employs one or morenon-planar metal-oxide-semiconductor transistors (MOSFETs). Generally,the non-planar transistor structure, also known as a finFET, offerssignificantly lower leakage current (e.g., by ˜50%) relative a twodimensional, or planar FET, during normal operation (i.e., when there isno ESD event occurring). The reduced leakage is, at least in part,because of greater gate control of the channel region (e.g., channel issurrounded on two, three, or even four sides for a gate all around ornanowire design) which more effectively suppresses sub-threshold or“off-state” leakage current. This reduced leakage ultimately reducespower consumption of snapback ESD protection devices. Furthermore, thenon-planar transistor structure enhances drive current when the ESDprotection device is in the “on” state (i.e., during an ESD event). Assuch, relative to a planar snapback ESD protection device, the higherESD current conductance offers more robust ESD protection for a givenarea of the chip.

FIG. 1A is a sectioned isometric view of a non-planar MOSFETelectrostatic discharge (ESD) protection device 101, in accordance withan embodiment of the present invention. As illustrated, the ESDprotection device 101 includes a plurality of non-planar semiconductorbodies, or fins 110 extending from a surface of a substrate 105. Aplurality of semiconductor fins 110 is advantageous for the protectiondevice 101 to provide robust ESD protection (i.e., high currentconduction capability). The number of semiconductor fins 110 coupled tothe gate electrode 140 may vary widely depending on application and onthe drive current achievable for a single fin, which is furtherdependent on z-height of the fins, etc. As such, while a plurality ofsemiconductor fins 110 is depicted as being an advantageous embodiment,single semiconductor fin embodiments are also envisioned. Althoughgeometries are transient being a function of the technology node, forthe exemplary 22 nm node, fins 110 may be expected to be 5-20 nm inwidth (y-dimension) and 20-60 nm in z-height. Generally, the fins 110and substrate 105 may be a same or different material (e.g., where finsare a hetero-epitaxial layer) and while the fins 110 are illustrated inthe exemplary embodiment as part of the bulk semiconductor of thesubstrate 105, in alternate embodiments, an insulator layer may separatethe fins 110 from the substrate 105 (e.g., as in an SOI substrate). Inthe exemplary embodiment, the fins 110 include silicon, and moreparticularly are single-crystalline silicon with other constituentslimited to electronically active dopant species. In other embodiments,the fins 110 comprise a compound semiconductor alloy, such as but notlimited to SiGe, III-N materials (e.g., GaN), or III-V materials (e.g.,InP, InSb, InAs, etc.). Similarly, while the substrate 105 is alsosingle-crystalline silicon, in other embodiments, the substrate 105 maybe any of the semiconductors listed for the fins 110, and may further bean insulator such as sapphire or SiC, etc.

As illustrated in FIG. 1A, the ESD protection device 110 furtherincludes a gate electrode 140 disposed over the plurality ofsemiconductor fins 110. The single gate electrode 140 extends over theplurality of semiconductor fins 110 to capacitively control a channelregion 120 in each of the semiconductor fins 110 in parallel. A sourceregion 115 and a drain region 125 are disposed in each of thesemiconductor fins 110 on opposite sides of the gate electrode 140. Thesource region 115 and drain region 125 are both heavily doped regions ofthe fins 110 and in the exemplary embodiment where the channel region120 is p-type, the source region 115 and drain region 125 are both dopedn-type to form a non-planar NMOS structure. The source regions 115 arecoupled in electrical parallel to source contact metallization 155 whilethe drain regions 125 are coupled in electrical parallel to the draincontact metallization 150. As shown, both the source contactmetallization 155 and the gate electrode 140 electrically coupled to oneor more integrated circuit (IC) nodes 160 having a same referencepotential, typically ground common to a core circuitry that theprotection device 101 is to protect. The drain contact metallization 150electrically couples the drain region 125 to a circuit node 170 disposedbetween an I/O (e.g., a pad or pin) of an IC and the core circuitrywhich the protection device 101 is to protect.

FIG. 2A is a schematic of a non-planar MOSFET configured for ESDprotection of CMOS circuitry coupled to an I/O pad, in accordance withan embodiment. As shown, an IC chip 201 includes core CMOS circuitry210, such as but not limited to, microprocessor logic gates, memorycells, etc. The CMOS circuitry 210 is electrically connected to an I/O205, through which the CMOS circuitry 210 interfaces with devicesexternal to the IC chip 201. The I/O 205 may be any conventional I/Opad, pin, post, wire, etc. The ESD protection device 101 (illustrated inFIG. 1A) is electrically connected to the circuit node 215 disposedbetween the CMOS circuitry 210 and the I/O 205. In the exemplaryembodiment illustrated in FIGS. 1A and 2A, a non-planar MOSFET is in agrounded-gate NMOS (ggNMOS) configuration. In this configuration, innormal operating mode, the ESD protection device 101 remains in an“off-state” with the channel region 120 conducting very little leakagecurrent because of the grounded gate electrode 140 being present onthree sides of the fins 110. Referring further to FIG. 1A, during an ESDevent at the node 170 coupled to an I/O of core circuitry, the voltage(V_(ESD)) at the drain region 125 increases, reversing the p-n junctionbetween the drain region 125 and substrate until avalanche breakdownoccurs. At this point, drain current increases, and holes generated(I_(gen)) drift towards a substrate contact (I_(sub)), increasing thebase voltage of the parasitic bipolar junction transistor (BJT) 177,which makes the base-emitter junction of the parasitic BJT 177 moreforward biased. As the base-emitter voltage increases, the parasitic BJT177 turns on. The drain voltage at turn-on of the BJT 177 is referred toas the trigger voltage (V_(t)) of the protection device 101. With theBJT 177 on, more current is generated and drain voltage required for agiven drain current falls in the negative differential resistance, or“snap-back,” regime of the protection device until the drain voltage isreduced to the holding voltage V_(h). The current conducted at V_(h) andthere beyond sinks ESD event current and protects the core circuitcoupled to the I/O node 170. This snapback ESD protection behavior isfurther illustrated in FIG. 3 as discussed elsewhere herein.

In embodiments, a non-planar MOSFET-based ESD protection device includesa lightly doped extended drain region. A lightly doped extended drainregion advantageously offers further reduced off-state leakage levelsduring normal operation and the ability to modulate snapbackcharacteristics of the protection device 101, either on a global ICchip-level or an I/O-core circuit dependent level. A lightly dopedextended drain region also advantageously permits critical dimensioningof the gate electrode 140 independent of voltage levels to be supportedby the ESD protection device. For example, even where a high voltage isto be supported by an ESD protection device a critical dimension of thegate electrode 140 may be the same as that employed in core circuitsconfigured to operate at significantly lower voltages. Depending on thegeometry of the lightly doped extended drain region (e.g., x-dimensionspacing vs. z-height, etc.), the relative impact on the off-stateleakage vs. on-state action of the parasitic BJT 180 may vary. Forexample, lightly doped drain region may pose a series resistance duringthe off-state that is more significant than during the on-state.Referring still to FIG. 1A, a lightly doped extended drain region 180 isdisposed in each of the semiconductor fins 110 and spaces the gateelectrode 140 apart from the drain region 125 by an amount greater thana spacing between the gate electrode 140 and the source region 115. Inother words, the fin distance 132 along the x-axis is longer than, or“extended” relative to, a corresponding distance between gate electrode140 and the source region 115 (which is generally controlled by athickness of dielectric spacer 145A disposed on the gate electrode 140).

As is shown in FIG. 1A, the lightly doped extended drain region 180extends through a z-height of the fins 110 that is greater than thatoccupied by the drain region 125. Furthermore, the lightly dopedextended drain region 180 extends along the x-dimension of the fins 110and is present on side of the drain region 125 opposite the gateelectrode 140. In other words, the drain region 125 is embedded withinthe lightly doped extended drain region 180. Generally, for theexemplary ggNMOS embodiment, the lightly doped extended drain region 180comprises an n-well disposed between the p-type channel region 120 andthe n-type drain region 125. In certain such exemplary embodiments, thelightly doped extended drain region 180 is doped n-type to 10¹⁶cm⁻³-10²⁰ cm⁻³ In further embodiments, the lightly doped extended drainregion 180 is disposed a distance 131 under the gate electrode 140 withthe distances 131 and 132 making up a total lightly doped extended drainlength 130 between the channel region 120 and the drain region 125.Generally, along with a critical dimension of the gate electrode 140(e.g., 22 nm, etc.), the distance 131 can be controlled through a wellimplant to set a desired base width of the parasitic BJT 180, whichimpacts V_(h) of the protection device 101, and as shown may besignificantly greater than a corresponding overlap between the sourceregion 115, or between an associated source region 115 lightly-doped tip(if present).

In embodiments, an extended drain non-planar MOSFET-based ESD protectiondevice includes a control gate. FIG. 1B is a sectioned isometric view ofan extended drain non-planar MOSFET 102 with a control gate 190 for ESDprotection, in accordance with an embodiment of the present invention.Structures and features common between the ESD protection device 101 andESD protection device 102 share the same reference numbers and anycharacteristics described for a particular structure in the context ofFIG. 1A is applicable to a like structure depicted in FIG. 1B.

Generally, the control gate 190 is capacitively coupled to at least aportion of the lightly doped extended drain region 180 and electricallyinsulated from the gate electrode 140 so that the control gate 190 iselectrically independent from the gate electrode 140 to the extent thatthe control gate 190 may be at a different electrical potential than thegate electrode 140. In the exemplary embodiment, both the gate electrode140 and the control gate 190 are capacitively coupled to thesemiconductor fins 110 through a same dielectric 138. The dielectric 138may be any “gate” dielectric known in the art, with the exemplaryembodiment employing a high-k dielectric material (e.g., having a bulkdielectric constant that is higher than that of silicon nitride).Exemplary embodiments of the dielectric 138 include, but are not limitedto hafnium oxide, zirconium oxide, and alloys thereof (includingsilicates). While the control gate 190 may be of any material, in theexemplary embodiment the control gate 190 is of the same material(s) asthat of the gate electrode. For example, in one ggNMOS embodiment, boththe gate electrode 140 and control gate 190 include a same high workfunction metal.

As illustrated in FIG. 1B, the control gate 190 is electrically isolatedfrom both the gate electrode 140 and the drain contact metallization150. In the illustrative embodiment, the control gate 190 is disposedmore proximate to the drain contact metallization 150 than it is to thegate electrode 140. In other words, the control gate 190 is spaced apartfrom the gate electrode 140 by a distance 134, along the x-dimension ofthe fins 110, which is greater than a distance between the control gate190 and the drain contact metallization 150. In one such embodiment, thelateral spacing between the control gate 190 and the drain region 125 isthe same as the spacing between the gate electrode 140 and the sourceregion 115 with the thickness of the dielectric spacer 145A between thegate electrode 140 and source contact metallization 155 being beapproximately the same as the thickness of the dielectric spacer 145Cbetween the control gate 190 and the drain contact metallization 150. Infurther embodiments, the distance 134 is approximately equal to thex-dimension (length) of the source and drain contact metallizations 155,150, respectively. For the illustrated embodiment, the protection device102 incorporates the control gate 190 in a manner that provides aphysically symmetrical architecture which may be advantageouslyfabricated with no additional masking operations beyond those used tofabricate the ESD protection device 101 illustrated in FIG. 1A.

Generally, for ESD protection device embodiments with a control gate,snapback characteristics may be further modulated through an electricalpotential applied to the control gate. For embodiments represented byFIG. 1B, therefore, the control gate 190 is to control charge carrierdepletion or accumulation within the lightly doped extended drain region180 to adjust a snapback characteristic (e.g., holding voltage V_(h),current at on-state, etc.) of the device 102. In embodiments, thecontrol gate 190 is coupled to a control gate voltage source 195 whichprovide as control gate voltage V_(eg). Generally, the control gatevoltage source 195 may set the control gate 190 to any control gatevoltage independent of the gate electrode 140. In certain embodiments,the control gate voltage source 195 floats the control gate 190, toprovide a predetermined default extended drain resistivity or resistancefor the ESD protection device 102. In another embodiment, the controlgate voltage source 195 sets the control gate 190 to a predeterminedcontrol gate voltage potential that is neither floating nor thereference potential of the gate electrode 140 (e.g., common ground of aprotected core circuit). Depending on the applied control gate biasvoltage, carrier depletion of the extended drain may be induced toincrease the effective channel resistance or carrier accumulation of theextended drain may be induced to reduce the effective channelresistance. For example, the control gate voltage source 195 may set thecontrol gate 190 to a predetermined voltage potential betweenapproximately 0.5 and 1.2V for an exemplary ggNMOS device having anextended drain with n-type doping level in the range described elsewhereherein.

In embodiments, a plurality of extended drain non-planar MOSFETs areconfigured for ESD protection of a plurality of core circuits. FIG. 2Bis a schematic of a plurality of extended drain non-planar MOSFET-basedESD protection devices 102A, 102B and 102N configured for ESD protectionof a plurality of CMOS circuitry, in accordance with embodiments. Asillustrated, the IC chip 202 includes a first core CMOS circuit 210Aconnected to a first I/O 205A, with the first ESD protection device 102Aconnected at a node 215A disposed there between. Disposed over a secondarea of the IC chip 202 is a second CMOS circuitry 210B connected to asecond I/O 205B, with the second ESD protection device 102B connected ata node 215B disposed there between. Disposed over a third area of the ICchip 202 is a high voltage MOSFET-based circuitry (HVMOS) 211 connectedto an I/O 205N, with the ESD protection device 102N connected at a node215N disposed there between. Notably, while the ESD protection devices102A-102N have extended drains, the core circuits may utilize non-planarMOSFETs which lack any such extended drain. As one example, wherein theCMOS circuit 210A is low voltage circuit and comprises one or morenon-planar MOSFETs, no extended drain is provided, the absence of whichresults in a nominal transistor source-drain resistance R_(sd). Infurther embodiments, at least one of the non-planar MOSFETs in the highvoltage circuit HVCMOS 211 includes an extended drain region imparting arelatively higher R_(sd) than found in any of the non-planar MOSFETsfound in the low voltage CMOS circuit 210A. As such, the non-planarextended drain MOSFET-based ESD protection device architecturesdescribed herein are compatible with a range of core circuitarchitectures.

In the illustrative embodiment, each of the ESD protection devices 102A,102B and 102N include a non-planar ggNMOSFET with an extended drain anda control gate, substantially as is illustrated in FIG. 1B. As furtherillustrated in FIG. 2B, a plurality of control gate voltage sources195A, 195B, and 195N are separately coupled to the ESD protectiondevices 102A, 102B, and 102N, respectively. While each of the ggNMOSFETsare have gate electrodes and source regions held at a referencepotential (e.g., ground), the control gate voltage sources 195A, 195B,and 195N are independently controllable to predetermined voltagepotentials V_(eg,1), V_(eg, 2), and V_(eg, n), respectively, that areother than the reference (ground) potential. FIG. 2C is a flow diagramillustrating operation of a plurality of the extended drain non-planarMOSFETs configured for ESD protection, in accordance with furtherembodiments. The method 295 begins at operation 296 with the IC chip 202illustrated in FIG. 2B. At operation 298, predetermined control gatebias voltages are applied, for example through control gate voltagesources 195A, 195B, and 195N. In embodiments, predetermined control gatevoltage potentials V_(eg,1), V_(eg, 2), and V_(eg, n) are selected toadjust a snapback voltage of each ESD protection device based on acharacteristic of the core circuit to which the ESD protection device iscoupled (e.g., received at operation 297A). As such, the robustness ofthe ESD protection and/or power consumption associated with a particularESD device may be tailored based on the core circuit requirements. Oneexemplary characteristic is a nominal operating voltage of a corecircuit. For example, a core circuit operating at higher operatingvoltages may be coupled to an ESD device configured with a control gatebiased to properly handle (i.e., remain in an off-state) higher voltagesignals induced/received on an associated I/O. A core circuit operatingat a lower operating voltage may be coupled to an ESD device configuredwith a control gate biased to properly handle (i.e., shunt current in anon-state) signals exceeding the expected lower voltages induce/receivedon an associated I/O. As such, a given voltage level permitted on oneI/O of a chip may be shunted on another I/O as an ESD event.

Referring still to the illustrative embodiment in FIG. 2B, where theHVCMOS circuit 211 has a higher nominal operating voltage than does theCMOS circuit 210A, the control gate voltage V_(eg,n) may be differentthan V_(eg,1) to increase the extended drain resistance R_(d,n) in theESD protection device 102N relative to R_(d,1) associated with the ESDprotection device 102A. In certain such embodiments where the lowvoltage CMOS circuit 210A is operable at voltages no greater than 1.5Vwhile the high voltage HVMOS circuit 211 is operable at voltages between1.5 and 3.3V and the control gate voltages V_(eg,1) and V_(eg,n) areboth between 0V and 1.2V for one exemplary non-planar ggNMOSimplementation. A similar modulation may further be practiced betweenthe two CMOS circuits 210A and 210B where the two have differentoperating voltages (e.g., CMOS circuit 210B being an ultralow powercircuit having a nominal operating point below 1.0V).

In further embodiments, performance of an associated ESD protectiondevice is modulated dynamically as a function of a core circuit statecharacteristic over time (e.g., at operation 297A changes in FIG. 2C) byvarying the control gate bias (e.g., at operation 298 in FIG. 2C). Forexample, where one or more of the core circuits 210A, 210B, or 211 mayon occasion enter a power save state (mode), or be placed into atemporarily disabled state, etc., one or more of the gate controlvoltages V_(eg,1), V_(eg,2), V_(eg,n) may bias the control gate of anESD protection device to modulate ESD protection device powerconsumption and/or robustness of ESD protection over time. Additionally,the presence of control gates and their further coupling to individualcontrol gate voltage potentials may be modulated post-fabrication toseparately account for variation in the IC fabrication processes (e.g.,input 297B) or variation in the application environment in which the ICchip 202 is subjected. With the control gate voltages set, the method295 continues with operation of the IC chip at operation 299.

While the exemplary embodiments described in the context of FIGS. 2B and2C illustrate advantages of the independent control gate biasing of ESDprotection device and, more particularly advantages of corecircuit-based ESD protection device control gate biasing, within asingle IC chip (such as for a mixed signal or SoC embodiments), theadvantages of such ESD protection device performance modulation are alsoapplicable in the context of a foundry process where a tunable ESDprotection device may enable standardization of ESD protection acrossASICs.

FIG. 3 is an I-V plot illustrating snap back characteristics for planarand non-planar MOSFET-based ESD protection devices of comparable currentcapacity during ESD events and normal operation, in accordance withembodiments. In FIG. 3, voltage of the device under test (DUT), and morespecifically drain voltage in the ggNMOS configuration, is on thex-axis, while the device current, and more specifically drain current,is on the y-axis. Notably, leakage levels of the planar ESD protectiondevice are significantly higher than the two exemplary non-planarprotection devices. In specific embodiments, where off-state leakage(during normal core circuit operation) for a planar ESD protectiondevice is approximately 1.5e-11 A/μm of channel width, off-state leakagefor the non-planar ESD protection devices describe herein areapproximately 4.2e-9 A/μm, or lower. Variation in current conduction isfurther illustrated in FIG. 3 for a non-planar MOSFET-based ESDprotection device having different control gate bias potentials,V_(eg,1) and V_(eg, 2). Also shown in a comparison of on-state currentbetween planar, non-planar devices and further for non-planar devices asa function of the different control gate bias potentials. Notably, theon-state current of the non-planar ESD protection devices is higher,more specifically for the embodiments having the leakage levelsdescribed above, the on-state current at 11V of drain voltage for theplanar ESD protection device is approximately 0.28 A/μm while theon-state current at 11V for the non-planar ESD protection devicesdescribed for embodiments herein is 0.4A/μm, or greater.

FIG. 4 is an isometric view and schematic of a mobile computing platform700 which employs an IC including extended drain non-planar MOSFET ESDcircuitry, in accordance with embodiments of the present invention. Themobile computing platform 700 may be any portable device configured foreach of electronic data display, electronic data processing, andwireless electronic data transmission. For example, mobile computingplatform 700 may be any of a tablet, a smart phone, laptop computer,etc. and includes a display screen 405 which in the exemplary embodimentis a touchscreen (capacitive, inductive, resistive, etc.), a chip-level(SoC) or package-level integrated system 710, and a battery 713.

The integrated system 710 is further illustrated in the expanded view720. In the exemplary embodiment, packaged device 777 includes at leastone memory chip (e.g., RAM), and/or at least one processor chip (e.g., amulti-core microprocessor and/or graphics processor) with core circuitrycoupled to an I/O and a non-planar ggNMOS ESD protection device disposedthere between. In embodiments, as described in more detail elsewhereherein, the ggNMOS ESD protection device includes a plurality ofsemiconductor fins having a lightly doped extended drain region disposedon a first side of a gate electrode, and spacing the gate electrodefarther from a heavily doped drain region of the semiconductor fin thana spacing between the gate electrode and a source region of thesemiconductor fin. The packaged device 777 is further coupled to theboard, substrate, or interposer 260 along with, one or more of a powermanagement integrated circuit (PMIC) 715, RF (wireless) integratedcircuit (RFIC) 725 including a wideband RF (wireless) transmitter and/orreceiver (e.g., including a digital baseband and an analog front endmodule further comprises a power amplifier on a transmit path and a lownoise amplifier on a receive path), and a controller thereof 711. Asillustrated, interfaces of each of these ICs includes an extended drainMOSFET-based ESD protection device 101, 102A, or 102N, where thesereference numbers represent the same devices described in the context ofFIGS. 1A, 1B, and 2B. In further embodiments, one, some or all of theextended drain MOSFET-based ESD protection devices employing within thepackaged device 777 include a control gate. In further embodiments, forexample in the ESD protection devices 102A and 102N illustrated in FIG.4, ESD protection device control gates are associated with differentcontrol gate bias voltages.

Functionally, the PMIC 715 performs battery power regulation, DC-to-DCconversion, etc., and so has an input coupled to the battery 713 andwith an output providing a current supply to all the other functionalmodules. As further illustrated, in the exemplary embodiment the RFIC725 has an output coupled to an antenna to provide to implement any of anumber of wireless standards or protocols, including but not limited toWi-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE 802.20,long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM,GPRS, CDMA, TDMA, DECT, Bluetooth, derivatives thereof, as well as anyother wireless protocols that are designated as 3G, 4G, 5G, and beyond.In alternative implementations, each of these board-level modules may beintegrated onto separate ICs coupled to the package substrate of thepackaged device 777 or within a single IC (SoC) coupled to the packagesubstrate of the packaged device 777.

FIG. 5 is a functional block diagram of a computing device 1000 inaccordance with one embodiment of the invention. The computing device1000 may be found inside the platform 700, for example, and furtherincludes a board 1002 hosting a number of components, such as but notlimited to a processor 1004 (e.g., an applications processor) and atleast one communication chip 1006. In embodiments, at least one of theprocessor 1004 and communication chip 1006 incorporate extended drainnon-planar MOSFET-based ESD protection devices. The processor 1004 isphysically and electrically coupled to the board 1002. The processor1004 includes an integrated circuit die packaged within the processor1004. The term “processor” may refer to any device or portion of adevice that processes electronic data from registers and/or memory totransform that electronic data into other electronic data that may bestored in registers and/or memory.

In some implementations the at least one communication chip 1006 is alsophysically and electrically coupled to the board 1002. In furtherimplementations, the communication chip 1006 is part of the processor1004. Depending on its applications, computing device 1000 may includeother components that may or may not be physically and electricallycoupled to the board 1002. These other components include, but are notlimited to, volatile memory (e.g., DRAM), non-volatile memory (e.g.,ROM), flash memory, a graphics processor, a digital signal processor, acrypto processor, a chipset, an antenna, touchscreen display,touchscreen controller, battery, audio codec, video codec, poweramplifier, global positioning system (GPS) device, compass,accelerometer, gyroscope, speaker, camera, and mass storage device (suchas hard disk drive, solid state drive (SSD), compact disk (CD), digitalversatile disk (DVD), and so forth).

At least one of the communication chips 1006 enables wirelesscommunications for the transfer of data to and from the computing device1000. The term “wireless” and its derivatives may be used to describecircuits, devices, systems, methods, techniques, communicationschannels, etc., that may communicate data through the use of modulatedelectromagnetic radiation through a non-solid medium. The term does notimply that the associated devices do not contain any wires, although insome embodiments they might not. The communication chip 1006 mayimplement any of a number of wireless standards or protocols, includingbut not limited to those described elsewhere herein. The computingdevice 1000 may include a plurality of communication chips 1006. Forinstance, a first communication chip 1006 may be dedicated to shorterrange wireless communications such as Wi-Fi and Bluetooth and a secondcommunication chip 1006 may be dedicated to longer range wirelesscommunications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, andothers.

The preceding paragraphs describe many exemplary embodiments. In oneembodiment, for example, an electrostatic discharge (ESD) protectiondevice includes a plurality of semiconductor fins extending from asubstrate with a gate electrode disposed over the plurality ofsemiconductor fins; a source region and a drain region disposed in eachof the semiconductor fins on opposite sides of the gate electrode,wherein the source region and the gate electrode are electricallycoupled to one or more integrated circuit (IC) nodes having a sameground reference potential, wherein and the drain region is electricallycoupled to a circuit node disposed between an I/O of the IC and corecircuitry of the IC coupled to the I/O; and a lightly doped extendeddrain region disposed in the semiconductor fins and spacing apart thegate electrode from the drain regions by an amount greater than aspacing between the gate electrode and the source regions. In furtherembodiments, a control gate is disposed over the semiconductor finsbetween the gate electrode and the drain regions, wherein the controlgate is capacitively coupled to at least a portion of the extended drainregion and electrically insulated from the gate electrode. In furtherembodiments, the control gate is to control charge carrier depletion oraccumulation within the extended drain region to adjust a snapbackholding voltage of the device. In further embodiments, a control gatevoltage source is coupled to the control gate, wherein the control gatevoltage source is to set the control gate to a predetermined controlgate voltage potential other than the gate electrode referencepotential. In further embodiments, the control gate and the gateelectrode are of a same material and are capacitively coupled to thesemiconductor fins through a same gate dielectric, wherein the controlgate is spaced apart from the drain region by an amount less than aspacing between the gate electrode and the control gate. In embodiments,the semiconductor comprises silicon doped p-type below the gateelectrode, wherein the source and drain regions are heavily dopedn-type, wherein the extended drain region is doped n-type to 10¹⁶cm⁻³-10²⁰ cm⁻³, and wherein on-state current of the device is at least0.4 A/μm of channel width or a drain voltage of 11V.

In embodiments, an integrated circuit device, includes: a plurality ofcore circuits disposed over a substrate; a plurality of I/Os disposedover the substrate, wherein each of the core circuits is coupled to atleast one of the I/Os to interface the core circuits with one or moreexternal devices; a plurality of electrostatic discharge (ESD)protection devices, each ESD protection device coupled to a nodedisposed between at least one of the core circuits and at least one ofthe I/O pins or pads, wherein each of the ESD protection devicescomprise an extended drain non-planar metal-oxide-semiconductor fieldeffect transistor (MOSFET) including: a plurality of semiconductor fins,each having a source region and drain region disposed on opposite sidesof a gate electrode disposed over the semiconductor fins; and a controlgate disposed over the semiconductor fins capacitively coupled to alightly doped extended drain region disposed in the semiconductor finsbetween the drain region and the gate electrode; and a plurality ofcontrol gate voltage sources coupled to the ESD protection devices,wherein ones of the control gate voltage sources are coupled to separatecontrol gates. In further embodiments of the integrated circuit device,the control gate voltage sources are independently controllable topredetermined voltage potentials other than the ground potential. Infurther embodiments, the predetermined voltage potentials are between0.5V and 1.2V.

In further embodiments, the predetermined voltage potentials adjust asnapback voltage of the ESD protection device based on a characteristicof the core circuit to which the ESD protection device is coupled. Infurther embodiments, the source, drain and extend drain regions aren-type, the gate electrode and the source region are coupled to circuitnodes at ground potential of the core circuits, and the first and secondcontrol gate potentials are between 0V and 1.2V. In further embodiments,the plurality of circuits further comprises: a low voltage circuitcoupled to a first of the I/Os and to a first of the ESD protectiondevices; and a high voltage circuit coupled to a second of the I/Os andto a second of the ESD protection devices, wherein the first ESDprotection device has a first control gate coupled to a first controlgate voltage source and the second ESD protection device has a secondcontrol gate coupled to a second control gate voltage source that is ata different control gate potential than the first control gate voltagesource. In further embodiments, the second control gate voltage sourceis at a control gate voltage potential that increases the resistance ofextended drain region of second ESD protection device relative to thatof the first ESD protection device. In further embodiments, the lowvoltage circuit and high voltage circuit both further comprise one ormore non-planar MOSFET, and wherein at least one of the non-planarMOSFETs in the high voltage circuit includes an extended drain regionhaving a higher source-drain resistance that of any of the non-planarMOSFETs in the low voltage circuit. In further embodiments, the lowvoltage circuit is operable at voltages no greater than 1.5V and whereinthe high voltage circuit is operable at voltages between 1.5 and 3.3V.

In embodiments, a method of operating non-planar ggNMOS ESD protectiondevices coupled to an integrated circuit (IC), the method includescoupling a gate electrode of a first of the non-planar ggNMOS ESDprotection devices to ground potential, wherein the gate electrode iscapacitively coupled to a non-planar semiconductor body and spacedapart, by a lightly-doped extended drain, from a heavily doped draincoupled to an I/O of the integrated circuit by a spacing greater thanthat between the gate electrode and a heavily doped source region of thesemiconductor fin; and setting a control gate electrically insulatedfrom the gate electrode, and capacitively coupled to the extended drain,to a different voltage potential than the gate electrode. In furtherembodiments, the method includes coupling a gate electrode of a secondof the non-planar ggNMOS ESD protection devices to a ground potential;and setting a control gate of the second of the non-planar ggNMOS ESDprotection devices to a different voltage potential than that of thefirst of the non-planar ggNMOS ESD protection devices.

In embodiments, a mobile computing device includes a processor with corecircuitry coupled to an I/O and a non-planar ggNMOS ESD protectiondevice disposed there between, wherein the ESD protection deviceincludes a plurality of semiconductor fins having a lightly dopedextended drain region disposed on a first side of a gate electrode, andspacing the gate electrode farther from a heavily doped drain region ofthe semiconductor fin than a spacing between the gate electrode and asource region of the semiconductor fin; a display screen; an RFtransmitter or receiver; and an antenna. In further embodiments, thenon-planar ggNMOS ESD protection device further comprises a control gatecapacitively coupled to the lightly doped extended drain region, whereinthe control gate is electrically insulated from the gate electrode andat a different potential than the gate electrode. In furtherembodiments, the processor and RF transmitter or receiver are on asingle integrated circuit (IC) as components of a system on a chip (SoC)and wherein the RF transmitter or receiver further comprise second corecircuitry coupled to a second I/O and a second non-planar ggNMOS ESDprotection device disposed there between, wherein the second ESDprotection device has a control gate coupled to a second control gatevoltage source.

It will be recognized that the invention is not limited to theseembodiments so described, but can be practiced with modification andalteration without departing from the scope of the appended claims. Thescope of the invention should, therefore, be determined with referenceto the appended claims, along with the full scope of equivalents towhich such claims are entitled.

What is claimed is:
 1. An electrostatic discharge (ESD) protectiondevice, comprising: a semiconductor fin extending from a substrate witha gate electrode disposed over the semiconductor fin; a source regionand a drain region disposed in the semiconductor fin on opposite sidesof the gate electrode, wherein the source region and the gate electrodeare electrically coupled to one or more integrated circuit (IC) nodeshaving a same ground reference potential, wherein and the drain regionis electrically coupled to a circuit node disposed between an I/O of theIC and core circuitry of the IC coupled to the I/O, and wherein thedrain region has an uppermost surface; and a lightly doped extendeddrain region disposed in the semiconductor fin and spacing apart thegate electrode from the drain region by an amount greater than a spacingbetween the gate electrode and the source region, wherein the lightlydoped extended drain region has an uppermost surface approximatelyco-planar with the uppermost surface of the drain region.
 2. The deviceof claim 1, further comprising: a control gate disposed over thesemiconductor fin between the gate electrode and the drain region,wherein the control gate is capacitively coupled to at least a portionof the lightly doped extended drain region and electrically insulatedfrom the gate electrode.
 3. The microelectronic device of claim 2,wherein the control gate is to control charge carrier depletion oraccumulation within the lightly doped extended drain region to adjust asnapback holding voltage of the device.
 4. The device of claim 2,further comprising a control gate voltage source coupled to the controlgate, wherein the control gate voltage source is to set the control gateto a predetermined control gate voltage potential other than the gateelectrode reference potential.
 5. The device of claim 4, wherein thecontrol gate and the gate electrode are of a same material and arecapacitively coupled to the semiconductor fin through a same gatedielectric, wherein the control gate is spaced apart from the drainregion by an amount less than a spacing between the gate electrode andthe control gate.
 6. The device of claim 1, wherein the semiconductorcomprises silicon doped p-type below the gate electrode, wherein thesource and drain regions are heavily doped n-type, wherein the lightlydoped extended drain region is doped n-type to 10¹⁶ cm⁻³-10²⁰ cm⁻³, andwherein on-state current of the device is at least 0.4 A/μm of channelwidth or a drain voltage of 11V.
 7. An integrated circuit device,comprising: a plurality of core circuits disposed over a substrate; aplurality of I/Os disposed over the substrate, wherein each of the corecircuits is coupled to at least one of the I/Os to interface the corecircuits with one or more external devices; a plurality of electrostaticdischarge (ESD) protection devices, each ESD protection device coupledto a node disposed between at least one of the core circuits and atleast one of the I/O pins or pads, wherein each of the ESD protectiondevices comprise an extended drain non-planar metal-oxide-semiconductorfield effect transistor (MOSFET) including: a semiconductor fin having asource region and drain region disposed on opposite sides of a gateelectrode disposed over the semiconductor fin, wherein the drain regionhas an uppermost surface; and a control gate disposed over thesemiconductor fin capacitively coupled to a lightly doped extended drainregion disposed in the semiconductor fin between the drain region andthe gate electrode, wherein the lightly doped extended drain region hasan uppermost surface approximately co-planar with the uppermost surfaceof the drain region; and a plurality of control gate voltage sourcescoupled to the ESD protection devices, wherein ones of the control gatevoltage sources are coupled to separate control gates.
 8. The integratedcircuit device of claim 7, wherein the control gate voltage sources areindependently controllable to predetermined voltage potentials otherthan the ground potential.
 9. The integrated circuit device of claim 8,wherein the predetermined voltage potentials are between 0.5V and 1.2V.10. The integrated circuit device of claim 8, wherein the predeterminedvoltage potentials adjust a snapback voltage of the ESD protectiondevice based on a characteristic of the core circuit to which the ESDprotection device is coupled.
 11. The integrated circuit device of claim10, wherein the source, drain and lightly doped extended drain regionsare n-type, the gate electrode and the source region are coupled tocircuit nodes at ground potential of the core circuits, and the firstand second control gate potentials are between 0V and 1.2V.
 12. Theintegrated circuit device of claim 10, wherein the plurality of circuitsfurther comprises: a low voltage circuit coupled to a first of the I/Osand to a first of the ESD protection devices; and a high voltage circuitcoupled to a second of the I/Os and to a second of the ESD protectiondevices, wherein the first ESD protection device has a first controlgate coupled to a first control gate voltage source and the second ESDprotection device has a second control gate coupled to a second controlgate voltage source that is at a different control gate potential thanthe first control gate voltage source.
 13. The integrated circuit deviceof claim 11, wherein the second control gate voltage source is at acontrol gate voltage potential that increases the resistance of thelightly doped extended drain region of the second ESD protection devicerelative to that of the first ESD protection device.
 14. The integratedcircuit device of claim 12, wherein the low voltage circuit and highvoltage circuit both further comprise one or more non-planar MOSFET, andwherein at least one of the non-planar MOSFETs in the high voltagecircuit includes an extended drain region having a higher source-drainresistance that of any of the non-planar MOSFETs in the low voltagecircuit.
 15. The integrated circuit device of claim 12, wherein the lowvoltage circuit is operable at voltages no greater than 1.5V and whereinthe high voltage circuit is operable at voltages between 1.5 and 3.3V.16. A mobile computing device, comprising: a processor with corecircuitry coupled to an I/O and a non-planar ggNMOS ESD protectiondevice disposed there between, wherein the ESD protection deviceincludes a semiconductor fin having a lightly doped extended drainregion disposed on a first side of a gate electrode, and spacing thegate electrode farther from a heavily doped drain region of thesemiconductor fin than a spacing between the gate electrode and a sourceregion of the semiconductor fin, wherein the heavily doped drain regionhas an uppermost surface, and wherein the lightly doped extended drainregion has an uppermost surface approximately co-planar with theuppermost surface of the heavily doped drain region; a display screen;an RF transmitter or receiver; and an antenna.
 17. The mobile computingdevice of claim 16, wherein the non-planar ggNMOS ESD protection devicefurther comprises a control gate capacitively coupled to the lightlydoped extended drain region, wherein the control gate is electricallyinsulated from the gate electrode and at a different potential than thegate electrode.
 18. The mobile computing device of claim 17, wherein theprocessor and RF transmitter or receiver are on a single integratedcircuit (IC) as components of a system on a chip (SoC) and wherein theRF transmitter or receiver further comprise second core circuitrycoupled to a second I/O and a second non-planar ggNMOS ESD protectiondevice disposed there between, wherein the second ESD protection devicehas a control gate coupled to a second control gate voltage source.